Revieivs — Dr. H. Filliol — Mammals of Sansan. 277 



to treat tlie rocks as mineral aggregates and to describe their 

 structure and composition. The field-geologist is mainly concerned 

 with their mode of occurrence and origin ; and to him rock-names 

 are a necessity. We are glad to find that the needs of the field- 

 geologist are not neglected by Dr. Hatch. Eeferring to the classifi- 

 cation of the rocks, he says " Chemical composition (as far as the 

 percentage of silica is concerned) and mode of origin or occurrence 

 occupy a chief place. Mineralogical composition is, on account of 

 its extreme variability, allowed to play only a subsidary rd/e." la 

 this difficult task of furnishing a classification of the Igneous rocks, 

 Dr. Hatch has achieved success. 



IT. — Dr. H. Filhol on the Fossil Mammals of Sansan, 



Etudes sur les Mammiferes Fossiles de Sansan. Ann. Sci. Geol. 

 vol. xxii Art. 1 ; pp. 320, 46 plates. 



I'^HE small village of Sansan, near Auch, in the department of 

 Gers, has long been celebrated for the number of remains of 

 Mammals found in beds belonging to the Miocene Moyen of the 

 French geologists, and also for the beautiful state of preservation in 

 which many of these remains occur. The first in the field to under- 

 take the description of these specimens was the late M. Edouard 

 Lartet, but his investigations appear to have been hampered by the 

 lack of sufficient opportunities for illustrating his descriptions with 

 figures. This want was to a certain extent remedied by the late 

 M. Paul Gervais, Dr. Kowalevsky, and others ; but only certain 

 species or groups were fully treated, and we have never had any 

 attempt at a monograph of the Sansan Mammals since Lartet's 

 preliminary catalogue. 



In the work before us we now have the whole series of these 

 remains not only well described, but fully illustrated by excellent 

 plates ; and all who are interested in this branch of fossil zoology 

 owe a debt of gratitude to Dr. H. Filhol, of the Paris Museum, for 

 the execution of this laborious task. It appears that the Doctor has 

 been in the habit of paying periodical visits to the Sansan quarries 

 during the past three years, and has thiis succeeded in obtaining 

 a number of specimens which far surpass most of those hitherto 

 described. Many of Lartet's types have also been fully described 

 and figured for the first time. 



The total number of species of Mammals which Dr. Filhol recog- 

 nizes from these deposits is 78 ; these being arranged under the 

 heads of 42 genera. In this notice we shall only refer to a few of 

 the species which appear to us of especial interest. Before doing 

 so, we venture, however, to call attention to some instances of 

 carelessness on the part of the author which are exceedingly em- 

 barrassing to those who, like the present writer, have to record 

 new genera and species. To begin with, Dr. Filhol never states 

 which of the genera and species to which his name is appended are 

 mentioned for the first time. In the absence of any back reference, 

 it would, however, be natural to assume that when we meet with 



